Thermionic receiving device for wireless telegraphy and telephony



' May 20, 1930. J, UND 1,759,593

THERMIONIC RECEIVING DEVICE FOR WIRELESS TELEGRAPHY AND TELEPHONY Original Filed March 51, 1920 Mimi? Vbltage Patented May 20, 1930 HENRY JOSEPH ROUND, OF MUEiWELL LL, LONDON, ENGLAND, ASSIGNOR TO THE RADIO CORPORATION OF AIIIEBICA, OF NE'VV YORK, N. Y., A CORPORATION OF NEW YORK THERMIONIC RECEIVING DEVICE FOR WIRELESS TELEGRAPHY AND TELEPHONY Application filed March 31, 1920, Serial No. 376,175, and in Great Britain May 13, 1919.

Renewed Fe ruary 21, 1929.

.his invention relates to improvements in thermionic receiving devices for wireless 'telegraphy and telephony and has for ts object an increased magnification of signals.

In a d 'cnal application, iii no. 301,088, filed August 21, 1928, entitled lhermionic receiv ng devices, there is claimed that phe e or no present invention which relates to the transformer per se.

According to this invention two valves are coupled by means of a transformer formed oi resistance wire with an air core hereinafter cal ed a resistance transform r and so arranged that the ratio of inductance to ca pacity is as great as possible. More than two valves may be arranged in cascade, each. valve being coupled to the next US5118- former or" the hind already described. in some cases the two windings or" a transformer znay be connected through a condenser.

The inven on. is illustrated by the acccm panying dra' g, Figure 1 or which shows a series of valves in cascade with transformers between them. Figure 2 shows a number of curves illustratin the result obtained. In Fig. 1 F l1 F are filaments of three ta 1: which heated by a common battery E. (the grid G of the first valve and the filament ll are connected to an oscillatory circuit C coupled to an aerial l). The anode il of the first valve is connected to one end of a priend of which is connected do of a battery l-l in series The secondary S is connectel to the G and filament F of the second valve the anode A of which connected to one end of a primary P the other end of which is connected to the positive pole of the battery The secondary S is con nected to the grid G and filament F of the third valve. Each of the transformers P 5; P S is formed of resistance wire with an air core and the arrangements are such that the ratio of inductance to capacity is as great as possible. The two windings of the transformer may be connected through condensers O O if desired. By increasing the number of valves and of transformers the magnification of the signals may be inwe voltages obtained when the transformer greatly reduced but at the sa.. e time its maximum occurs at about the middle of the range of wave lengths to be dealt with. It will be seen that this curve is much flatter than the curve 1, that is, the magnification is considerably reduced the resonance point but hardly at at the limits of the wave lengths whei magnification still occurs. Curve shows the voltages that may be obtained by on ,iloying a number of valves and transformers shown in Figure 1 while curve l shows the effect when condensers such as C C are added.

By means of this invention it is possible to construct stable cascade amplifiers having a good range of wave length for waves even short as metres.

What I claim is l. A cou ,ing cevice "For thermionic ampli liers compr mg a primary coil, a secondary inductively coupled thereto, and a conof relatively high resistance Wire, a secondary coil constructed of relatively high resistance Wire, said coils being inductively coupled together, a condenser connected from one end of 5 said primary coil to one end of said secondary coil, the inductive reactance of said device being high in comparison to the capacitive reactance of said device.

4. A coupling device for thermionic amplim fiers comprising a primary coil containing inductive reactance and damping resistance, a secondary coil containing inductive reactance and damping resistance, said coils being provided With an air core and a condenser connected between one end of said primary coil and one end of said secondary coil.

5. A coupling device for thermionic amplifiers comprising a primary coil having inductive reactance, a secondary coil having an inductive reactance, each of said coils being highly damped and each offering a relatively high reactance to a predetermined frequency band, said primary and secondary coils being inductively coupled, means for capacitively coupling said coils, said means offering a rela tively low reactance to said frequency band.

A coupling device for amplifiers of electrical oscillations designed to produce a substantially uniform voitage response over a :0 predetermined range of frequencies comprising a primary coil, a secondary coil inductively coupled thereto, a condenser connected between one terminal of said primary coil and one terminal of said secondary coil, said coils 85 having an inductive reactance relatively high with respect to the capacitive reactance of said condenser.

7. In a system of the class described, means to couple two three-electrode vacuum tubes together, whereby to permit a substantially uniform transfer of energy from one tube to the other over a predetermined range of frequencies, said means comprisin a primary coil connected to one vacuum tube, a

5 secondarv coil connected to another vacuum tube anu coupled to said primary coil, said primary coil and secondary coil coupled thereto having together a high ratio of inductance to capacity, and a capacity other than the capacity inherent in said coils connected from the plate of one vacuum tube to the grid of the other vacuum tube.

HENRY JOSEPH ROUND. 

